Method of treating ore material with a complex brine



Oct. 23, 1934. R. l.. SESSIONS 1,977548 METHOD OF TREATING ORE MATERIALWITH A COMPLEX BRINE Filed May 5. 1932 H SO CoMmorPeoezss 0R: BR-INENOI. L a 4 l Phs Naci Mzzoo, Nag S04. disq HCI P/QMENT' ROYAL L.Sess/ons Patented ct. 23, 1934 UNITED STATES PATENT OFF-.ICEA

ME'rnon or TREATTNG oar: MATERIAL wrm A COMPLEX BRINE Royal L. Sessions,Denver, Colo., assignor, by

mesne assignments, to Hughes-Mitchell Processes, Incorporated, Denver,Colo.; a corporation of Wyoming Application May 5, 1932, serial No.609,361

16 Claims.

found it to be feasible toemploy in a series of hydrometallurgical stepsa complex brine containing a mixture of the carbonate, the sulfate andthe chloride ofran alkali metal, such as sodium, which has heretoforebeen considered a material of little practical or commercial valuebecause of the expense involved in separating the different saltstherein.

The primary object of my invention is to so arrange and coordinatevarious process steps that a complex brine of this type may be employedeffectively and economically in the treatment of complex ore materialsfor recovering values therefrom, in which the different acid ions areused serially to accomplish reactions for which they are adapted withoutdetrimentally aiecting other constituents of the ore materialbeingtreated.

A further object is to so treat the brine that undesired constituentsmay be removed and a desired salt or mixture of salts recovered, and toemploy such a series of steps that the process of purification iscommercially practical and so economical or self-supporting that thecost of recovering the. desired end product may be allocated to the costof treating the ore materials and thus make the process and the use orsale of the desired salt protable.

A further object of this invention is to so treat the brine cyclicallythat the carbonate and sulfate radicals may b e removed therefromeconomically while serving usefully in an ore treatment,

and the residual salt or-salts may be employed in the manufacture ofhydrochloric acid required.; for the production of an ore metal chloridewhich in turn aids in the process of purifying the brine.

A further object of the invention involves .the vtreatment of an \orematerial containing 'lead sulfate which resultsin the formation of leadcarbonate commerciallynfree/frm lead 4sulfate, and particularly toemploy the brine above described Ior this purpose.

With these and other. objects in view, as will be apparent to oneskilled in the art, my invention resides in the combination of processsteps set forth in the specication land covered by thel claims appendedhereto.

In order that the invention may be fully understood, I have describedherein a process of employing in the treatment of ore materials a brinewhich may have thefollowing composition:

Analysis of brine Analysis o! dry material It will, however, beunderstood that this invention is applicable to solutions and to amixture of their dry salts, which are derived from brines of thisgeneral class containing sodium or potassium chlorides, carbonates andsulfates, whatever may be the strength of the solution'or the exactproportions of the constituents in the brine or the dry salt mixture; aswell as to the mixture of salts obtained from either the original brineor the partially puried brines recovered from any stage of the process,which may be obtained by a complete or partial removal, as byevaporation, of the Water solvent. f w

I have found that this brine has great utility, if employed at theproper stages in the treatment of various ore materials, suc'h as acomplex sulfide ore, and particularly one containing compounds of zinc,copper and 4lead as Well as other desired metal values which are to berecovered. While the process is applicable to many ore materials,whether they are -raw oresfrich,v lean or concentrates, or they comprisepartially treated ores,A such as roasted and chloridiz'ed sulde ores,the invention is herein described withreference to a sulfide orecontaining zinc andlead which are to be separated and to the use of thevarious constituents of the brine as well as the recoveryA of sodiumchloride or a mixture of salts for sale A or reuse in the process.'I'his brine is herein conl salts.

the particular process herein described, it may be y assumed that thesolution will satisfy the following requirements for treating a lead andzinc sulfide ore concentrate calculated as the approximate amount of drybrine salts. necessary for precipitating all of the zinc and lead in 100tons of bulk ore concentrates: "f

For zinc-41 tons soda ash-'77 tons of dry brine salts.

For lead-8 tons soda ash-16 tons of dry brine On the basis that one-halfof the zinc is conver-ted to zinc sulfide and one-half to zinc oxide ormetal, the requirements are:'

For zinc 39 tons dry salts For lead 16 tons dry salts Total 53 tons drysalts 'This table shows that if the zinc content of the ore requires 41tons of soda ash lfor its treatment, then 77 tons of the dry salt of theabove analysis will serve the same purpose. Iese various iigures showthe practicability ofjithe process.

In order that the different a'spects of this invention may beunderstood, rejlefrence is had to the drawing, which illustratesJdiagrammatically a scheme including alternative' steps for thetreatment of a lead and zinc sulfldebre and for the use of this brine insuch ore treatment. The brine has a content of sodium carbonate which isextremely valuable in this process, in that it serves as a precipitatingagent for removing zinc, copper and lead from their solution's. It alsohas a content of chloridion which is useful in various ways, such as inthe manufacture of hydrochloric acid for treatment of the ore and indissolving the lead sulfate in the ore residue. The sulfate ion hasvarious uses, likewise, such as precipitating an alkaline earth metalfrom solution, as indicated on the drawing. The leady sulfate in an oreresidue may be converted to lead-"chloride by leaching with either a hotsolution of sodium chloride or a hot solution of the partially treatedbrine containing sodium -chloride and sodium sulfate and from which thesodium carbonate has been removed. In accordance'with a particularfeature of this invention, the lead chloride, which is dissolved in `thehot sodium chloride and sulfate solution, may be precipitated as leadcarbonate commercially free from lead sulfate by means of the completeor original brine containing the carbonate, sulfate and chloride ions,or by a solution otherwise derived containing sodium sulfate as well assodium carbonate, which acts in the presence of the sodiumchlorideemployed to hold the lead in solution as a chloride. It willvalso be 4apparent from inspection of the drawing, that salt cake, commonsalt, glauber salts. etc.

Assuming that the ore material to be treated comprises lead and zincsuliides along with various other materials constituting the gangue andwhich may contain other ore metal values, such as copper, iron etc., Imay proceed in accordance with the following process. The ore is firstcrushed to a suitable degree of flneness and is then roasted underoxidizing conditions and in accordance with any suitablel procedure toform zinc oxide and lead sulfate. 'I'he sulfur dioxide and trioxidegases derived from the roasting operation may be carried through acontact process and combined with water for the manufacture of sulfuricacid, and this acid may then be employed for the manufacture ofhydrochloric ac id by rei action with sodium chloride derived from alater stage in the process. It will also be particularly noticeable thatI may employ in making the HCl a mixture of sodium chloride and sodiumsulfate (brine No. 2) derived from this process, and that the sodiumsulfate which is there present will not only do no harm but will go withthe sodium sulfate formed during the process, thereby serving in a veryeiiicent way to take the chlorine ion out of the solution andconcentrate the sulfate ions in the sodium sulfate which in turn may beemployed in various desired ways.

'I'he hydrochloric acid derived from this process may then be utilizedto convert zinc oxide in the roasted ore material to zinc chloride. Anysuitable procedure may be employed for the purpose, but in accordancewith one preferred method the hydrochloric acidV is passed as a gas overthey substantially dry roasted ore material and thus serves to convertthe zinc oxide to chloride which may be separated from the ore materialby the simpe expedient of leaching with water. This leaves the leadsulfate with the ore gangue which will be treated in a subsequent stagefor the conversion of the lead compound to a chloride and then to acarbonate. We now have a solution of zinc chloride which serves` as ourrst reagent for initially removing the car-y bonate radical from thebrine.

The original brine containing the carbonate radical is labeled on thedrawing as Brine No. 1, and the material actually used in the processmay be derived from the dry salt formed by evaporation of the originalbrine or it may be the initial brine solution of any suitableconcentration, and the proportions of the several ingredients may bevaried as required for the particular step being carried out. Whatevertype of material is used will, of course, depend upon the desires of thechemist in charge of the operation and what economic results arerequired. This complex brinemay be derived from various sources, eitherartificial or natural. Because of its composition, such a brine hasheretofore been considered of little economic value. However, inaccordance with this procedure, it has now become the primary reagent ina commercially practical process. i

The carbonate radical in the brine may appear as sodium carbonate andsodium bicarbonate. By treating the zinc v chloride solution with thisbrine or the dry ingredients thereof in the required proportions, thecarbonate radical is removed from the brine, with the resultantprecipitation of zinc carbonate. The chlorine ion of the zinc chloridevremains in solution as sodium chloride, thus increasing the sodiumchloride 'content of the brine. This step is carried out with suitableconcentrations and proportions of the ingredients. The resultantsecond-stage solution is designated as Brine No. 2".

It is also to be understood that various other sources of this primaryreagent for removing new anion into the brine.

ltion has been so carried on as to produce zinc If the ore materialcontains copper sulfide or oxide, it may be chloridized in the samemanner as' the zinc and thus employed for removing carbonate from thebrine and precipitating copper carbonate. Likewise, lead chloridedissolved in a hot solution of sodium chloride, or brine No.2, as

' derived from later stages in the process or as obtained elsewhere, maybe used for this purpose and at this stage or other stages in theprocess.

Also, it will be understood that the soluble sulfates of various oremetals may be employed in the same manner, since these introduce no Ifthe roasting operasulfate, either alone onintermingled with zinc oxide',the zinc sulfate may be derived from the roasted ore by a leachingoperation, or all of the vzinc oxide -may be converted to a sulfate andthe latter recovered. This zinc sulfate may then be combined with thebrine, with the resultant precipitation of zinc carbonate and theremoval of the carbonate radical from the brine. The

zinc carbonate thus formed may be converted,

if desired, to the oxide by calcination and then reduced to the metal,yor it may be otherwise treated.

Whatever process stepx is used in this iirst stage, as above indicated,the resultant brine No. 2, which is now ready for use in a second stage,contains only the sodium, chlorine and sulfate ions along with thevarious impurities, or useful reagents added for desired purposes, whichmay be present in the brine. This partially purified brine consistingprimarily of sodium chloride and sodium sulfate may now be used invarious important process steps. For example, a portion of it may bepassed through the process for making hydrochloric acid and so result inthe removal of the chlorine ion from the brine and theI production of asolution high in sodium sulfate content. I prefer to carry a portion orall of the brine No. 2 through a iurther purification step where itssulfate ion is put to useful work. If it is desired merely to obtainsodium chloride for sale on the market or for use in the hydrochloriclacid process or elsewhere, then the next step of my process may involveremoving the sulfate radical by evaporating the solution andfractionally crystallizing out the sodium sulfate.

I have, however, found that vthe sulfate content of the brine isparticularly useful in the process or treating alkaline earth materialsand that in'turn the latter are useful in purifying -the brine, byprecipitating the sulfate radical as an insoluble sulfate. For example,zinc chloride derived from the ore inay be employed the manufacture ofthe pigment zinc sulfide. This is accomplished, in accordance withstandard procedure, by combining soluti'ohs of zinc chloride and bariumsuliide of required concentrations and molecular proportions, with theresultant =precipitation of zinc sulfide and leaving a solution ofbarium chloride. AIn order to regenerate the barium sulde required inthe process, this barium chloride solution may now .be treated with thesecond-stage brine No. 2.

This results in the precipitation of barium sulfate or blanc fixe, whichmay be separated from the solution and subsequently furnaced with carbonat a required temperature to reduce it to barium sulilde; and the lattermay then be leached from the furnace charge to re-form the barium sulderequired in the pigment-making process. 'I'his procedure, therefore,serves as a very simple way of utilizing this brine to make the pigmentprocess in part cyclic; The brine solution No. 3 which results fromgthetreatment y of the barium chloride with brine No. 2 is primarily made upof sodium chloride, and this may be returned for the hydrochloric acidmanufacture yor for commercial sale or otherwise used. as desired.

As an alternative procedure for removing the sulfate radical frombrineNo. 2, I may employ the chlorides of the other alkaline earth metals,calciumV and strontium. For example, limestone may be treated withhydrochloric acid to form calcium chloride and when'this isV combinedwith brine No. 2, a precipitate of calcium sulfate is formed. Also, thecalcium 'chloride may be derived from other stages'in the ore treatment.Likewise, strontium chloride may be formed in any suitable way andusedto precipitate strontium sulfate by 'means of the brine. Bariumchloride may also be derived fromV other sources besides that of makingpigment. For example,

witherite may be treated with hydrochloric acid to form barium `chlorideand this likewise used to form barium sulfate.` These examples indicatehow flexible is this process and that any suitable material capable ofremoving the sulfate ion as an insoluble material may be employed. I,however, prefer to use one of the alkaline earth metal chlorides abovespecified. i

The sodium 'chloride solutionl forming brine No. 3 is particularlyuseful for leaching lead sulfate from the roasted ore material.indicated in the drawing, the second-stage solution or brine No. 2containing both sodium chloride and sodium sulfate may be employed forthis leaching operation. In either case, the solution is kept hot andsuch conditions are employed as will serve to convert the lead sulfateof the ore to lead chloride. This step will be carried out in a suitableapparatus and according to standard proceduref Having now obtained asolution containing the lead as a chloride, the next step is to recoverthe lead; anda further discovery resides in the fact that the brine ofthe first stage is serviceable for producing lead carbonate which iscommercially free from lead sulfate. This is important, since it nowmakes it possible to obtain lead carbonate and lead oxide .,orthe metalby the very simple and economical procedure of leaching the lead sulfatefrom the ore residue as a lead chloride by means of hot brine No; 2 orbrine No. 3 and then precipitating the lead from this 'hot salt solution`by means of brine No. l ora suitable solution containing sodiumcarbonate. The precipitate of lead carbonate thus formed from thissolution may be removed by hltration, leaving a solution containingsodium chloride and sodium sulfate which may be returned, as indicated,to various lstages in the process for use as brine No. 2.

, It `will now be appreciated that one feature of this inventioninvolves utilizing a complex brine of this nature in which the carbonateradi- Also, as

cal may be rst removed as an insoluble zinc, copper or lead carbonate,after which the sulfate radical is removed as an alkaline earth metalsulfate which is insoluble in the brine and 5 finally the sodiumchloride content, or brine No.

' another.

2, may be employed for removing the sulfate radical from lead sulfate asa soluble sodium salt. 'I'his makes the treatment of a complex zlncandlead ore simple Tand efficient.

The word brine Where used in the specification and claims is to beinterpreted as covering not only a solution of the salts but also thedry salts derived by evaporating the brine, where the reagent can beemployed in the dry condition or after the dry salt has been obtainedand then dissolved in water. If the dry salts are employed, they may incomposition from the original brine solution because of the fact thatfractional crystallization of the solution will bringv down rst one saltor mixture and then orated, the carbonates tend to crystallize first;but, unless expensive purificationvsteps are employed, the crudesodium*y carbonate thus crystallized out will be contaminated with aconsiderable amount of sodium sulfate and sodium chloride. Also, the drysalt may be suitably treated to change its composition. It is within thescope of my claims to employ such an impure crude salt in my process,and particularly since the process adds to the amount of -chloride andsulfate ions present in the reagent solution and there is no necessityor utility in initially removing them from the carbonate crystals.

It will also be appreciated that it is within the scope of my inventionto remove an excess of any anion from the brine or the dry salts at anystage in the process and particularly where the presence of a largequantity thereof hinders the process. For example, the presence of anex, cessive amount of sodium sulfate in the hot brine used for leachingthe lead from the ore residue may be found undesirable, and in that caseI I may take steps to eliminate some of this excess or employ a brinecontaining sodium chloride derived from some other stage in the processwh ch has a proper content of the acid ions for the process. However,since the reaction nomically desirable to employ the salt in the dry 1form for the purpose, and this is my preferred practice. In thisprocess, the HC1 is generated by the reaction of HaSO4 on the NaCl ofthe solution or the `dry salt.

In the various stages of the process requiring the use of sodiumcarbonate to precipitate an ore metal carbonate, the reactions proceedas follows:

Lead, copper and `so forth may be substituted for zinc in the equationsFrom these, it will be' seen that the process is effective to remove thecar- For example, when the brine is evap-l primary reagent furnishingdesired chemicals for the reaction. It will, of course, be understoodthat various other intermediate steps and purification processes may beemployed for removing other ore materials or for eliminating undesiredingredients. The analysis of the brine above given indicates that thereare various other elements therein which have not been utilized in thereactions, as above described. If desired, I may take the necessarysteps to purify the brine from these undesired ingredients at any stagein the process or I may 'so modify the process that these undesiredingredients will not produce detrimental reactions as they go along withthe brine solutions.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. The method of recovering a lead compound from a lead -bearing orematerial comprising the steps of forming lead sulfate from the oremate'- rial, leaching the ore material with a hot solution containingsodium chloride and forming a solution of lead chloride and sodiumchloride, and then treating said lead chloride solutionwith a brinecontaining sodium carbonate and sodium sulfate and forming a precipitateof lead carbonate which is commercially free from lead sulfate.

` 2. I'he method of forming lead carbonate from a solution containinglead chloride comprising the steps of precipitating lead carbonate fromthe solution by reaction with a brine containing sodiumcarbonate, sodiumchloride and sodium sulfate and Yproducing lead carbonate which issubstantially free from lead sulfate, and thereafter separating theprecipitate from the solution and recovering the lead carbonate.

3. The method of treating a complex ore material containing the sulfatesof leadr and zinc or copper comprising the steps of separating the zincor copper from the lead sulfate as a sulfate solution, treating thesolution with a brine comprising primarily the carbonate, sulfate andchloride of so'dium to precipitate the carbonate of zinc or copper andform a brine substantially free from the carbonate radical, and leachingthe lead sulfate from the ore residue by the carbonate free brine andthereby causing the complex brine to separate the ore values.

4. The method of recovering and using the carbonate content of a saltture containing the sodium salts of hydrochlo c, sulfuric and carbonicacids comprising the steps of adding the salt mixture to a hot solutioncontaining sodium and lead chlorides and precipitating lead carbonatetherefrom, while leaving substantially all Vof the chlorine and sulfateions in solution, cryscontaining lead sulfate and form a solutioncontaining lead and sodium chlorides for further rei action with saidsalt mixture, whereby the latter serves to recover. lead from an ore aslead carbonate.

5. The method of treating an ore material containing copper, lead orzinc comprising'. the steps of removing the desired metal from the oreresidue as a chloride or sulfate solution, treating the solution with abrine comprising primarily the sulfate, carbonate and chloride of sodiumand precipitating an ore metal carbonate therefrom, without introducinga new anion into the solution, and providing a second stage brinecomprising primarily the sulfate and chloride of sodium which issubstantially free from a carbonate, and thereafter treating the secondstage brine with an alkalneearth metal chloride to precipitate thesulfate radical therefrom as alkaline earth'metal sulfate, therebyleaving a brine comprising primarily the chloride of sodium, whereby anore metal is recovered and sodium chloride is derived from said complexbrine. i

6. The method according to claim 5 in which the alkaline earth metalchloride is barium or calcium. y

'1. The method'of treating an ore containinga metal of the groupcomprising zinc and lead comprising the steps of converting the zinc toa sulfate or chloride in solution, treating the solution with a brinecomprising primarily the carbonate, sulfate and chloride of sodium inamount'suilicient to remove all of the carbonate from the brine andprecipitate zinc carbonate without introduclng a new anion into thebrine, recovering said zinc carbonate therefrom, thereafter. treatingthe resultant brine with the chloride of an alkaline earth metal whichis capable of and is propor- ,and forming an ore metal chloride,leaching the tioned'for precipitating the sulfate radical in the brineas an insoluble Nalkaline earth metal sulfate,

thereby producing a brine solution consistingl comprising the steps ofchloridizing the ore metal f and separating it from the lead sulfate andore residue as an ore metal hloride solution, treating said solutionwith a brine comprising primarily the sulfate, carbonate and chloride ofsodium to precipitate the metal as a carbonate andremove the carbonateradical from the brine, treating the resultant second stage brine withan alkaline earth metal chloride to precipitate the sulfate radicaltherefrom and provide a third stage brine comprising primarily thechloride of sodium, and treating the ore residue with the third stagebrine to form a solution of lead chloride, and thereby employing anionsof the brine serially to vrecover and separate the values oi a complexore.

9. The method oi chloridizing an ore containing a metal oxide comprisingthe steps of treating the ore with hydrochloric acid'to form .an oremetal chloride, leaching the chloride'froln the ore residue, treatingthe chloride in solution with a complex salt comprising primarily thecarbonate, sulfate and chloride of sodium to precipitate the ore metalas a carbonate and form a second stage brine substantially free from thecarbonate. radical, and treating the combined second stage brine saltswith sulfuric acid to form said hydrochloric acid fior chloridizing theore, and thereby using said complex brine both as a source of chlorinefor the ore treatment and to separate an ore value from the residue.

l0. vllhe method of treating an ore material containing a zinc compoundcomprising the steps of forming zinc chloride therefrom, treating zincchloride with a brine comprising sodium sulfate, carbonate and chlorideto remove the carbonate treating zinc chloride with barium sulde to formzinc sulfide and a solution of barium chloride, and combining the bariumchloride solution with the resultant brine in the second stage toremo've the sulfate radical therefrom as insoluble barium sulfateand-leave a brine consisting primarily of sodium'chloride.

11. The method of treating a Vcomplex ore material comprising the stepsof converting values thereof to an `ore metal chloride or sulfate,treating the latter in solution with a complex brine comprisingprimarily the sulfate, carbonate and chloride of sodium andprecipitating the carbonate radical as lan ore metal carbonate withoutintroducing a new anion into l taining the oxide of zinc or coppercomprising the steps of treating the ore with hydrochloric acid metalchloride from the residue, treating the chloride in solution with acomplex brine comprising 'primarily the carbonate, vsulfate and chlorideof sodium to precipitate said metal as a carbonate, treating the secondstage brine with an alkaline earth metal chloride to precipitate thesulfate radical therefrom and leave a salt Y brine substantially freefrom the sulfate radical,

treating the sodium chloride of the resultant salt withsulfuric acid togenerate said hydrochloric radical from the brine and to form zinccarbonate,

acid, and thus causing chloridion derived from the original complexbrine to chloridize the ore. 14. The method of treating an orecontaining zinc and lead sulfides comprising thesteps of chloridizingthe ore to form zinc chloride and lead sulfate, dissolving the zincchloride from the ore and treating it with a brine containing sodiumcarbonate, sulfate and chloride to precipitate the carbonate radical aszincy carbonate, leaching the lead sulfate from the ore residue by a hotbrine containing sodium chloride and sulfate and treating ythe,resultant lead chloride solution with some of the original brine toprecipitate lead carbonate commercially free from lead sulfate and leaveA.a brine containing sodium chloride and sulfate for further use in theprocess. l5. The method of treating a roasted sulhde ore materialcontaining lead sulfate and a zinc compound comprising the steps oftreating the material with a chloridizing agent to form zinc chloride,separating the zinc chloride from the lead compounds in the ore residue,treating the zinc chloride in solution with barium sulfide toprecipitate zinc sulde therefrom and form a barium chloride solution,treating the latter with a brine comprising primarily the sulfate andchloride of sodium to precipitate the sulfate radical as barium sulfateand form a sodium chloride brine, reducing the barium sulfate to thesulilde for reuse'in making zinc sulfide, and dissolving the lead fromthe `residue by means of said sodium chloride brine, whereby the brineserves serially in the recovery of both the zinc and lead in the ore.

i6. |The method of treating a zinc bearing ore ore by means of analkaline earth metal sulilde to form zinc` sulde and alkaline earthmetal chloride, separating said products and treating the brine in thesecond stage with the alkaline earth metal chloride to remove thesulfate radical therefrom, thereby forming a solution consistingprimarly of sodium chloride and employing the brine in the recovery ofzinc Iromthe ore.

ROYAL L. snssroiqs.

